Optimizing 3D CAD Data Sets for Animation

Optimizing 3D CAD Data Sets for Animation

This year we’ve had the privilege of working on several fun projects with several long-time repeat clients. One of them was Milton Roy Mixing, an arm of Accudyne Industries | Milton Roy.

On left, the finished, rendered model. On the right, the wire frame representation of how it originally came in. Used with permission.

Translating existing 3D CAD data sets into functional 3D models for animation is step one. CAD data sets can be created in many different CAD software applications. Bringing these different file formats into the animation environment requires a flexible and competent workflow.

On complex assemblies such as machines with many parts this requires patience and attention to detail. Picking through complex CAD models with hundreds or thousands of parts can be a daunting task. Grouping parts and sub assemblies according to how they’ll be animated and textured is one example of how you might organize a data set preparing it for animation.

Often times CAD assemblies will come through with every screw, nut, bolt and widget required to build it properly in the real world. Any object visible to the camera contribute to a high degree of realism. The invisible objects hidden from a given shot are dead weight – only contributing to sluggish performance – and require removal.

Another example is having to remodel portions of the object. Often times the CAD translation process creates a model made up of far more polygons than necessary. Models can be initially optimized during the translation process with software and though a good first step – is not a complete solution. Just as an example, a simple cylinder may translate into many excess points and polygons, but in reality, could be re-created as a simple primitive which is much easier for rendering engines to work with. Though this article is about using existing 3D objects – the necessity to create completely new 3D components to repair objects that didn’t translate well is part of every project. This falls under the Modeling category and will be discussed later.

Smooth exterior housings can be especially difficult to render perfectly smooth. Often times creases and holes appear as a result of the translation process. Used with permission.

One final example is large, smoothly curved surfaces (think plastic, injection-molded exterior casings). Often times what should appear smooth and perfect instead appears with creases, edges or even worse – tears in the polygonal geometry. The culprits are rogue “edges” and “smoothing angles” that did not translate well. This can be one of the most difficult things to fix, requiring identifying the offending “edge” and working to resolve the issue. Sometimes you’ll think you’ve got it perfect, then test render from different angles with different light – and sure enough, there it is. Rats!

All of this work is considered Optimizing the model for animation. It’s time consuming but worth it, the end result being a perfect 3D replica of the device properly set up to behave as it would in the real world: accept any motion, camera angle or close-up.

Milton Roy Side Entry Mixer. Used with permission.

In animation there are always ways to work around an imperfect model, especially if you’re only viewing it from one angle. If the camera doesn’t see it, it’s not there. But in 360° degree rotations or high-resolution still images for marketing it’s impossible to hide imperfections and everything needs to be done right.

CAD translation and optimization is a core competency at CraneDigital. It takes time and attention to detail, but is absolutely necessary to ensure a high-quality project is delivered. Once complete, the model is then ready for any assignment required by the client.

This series of blog posts is designed to help clients understand a little about how the process works. One pledge to our clients is to not bog them down with confusing technical details. But on the other side to that is providing some explanation of the time something takes.